Muffler



March 1940- c. HOLLERITH ET AL MUFFLER Filed Oct. 6, i957 gwumvbo'td CHARLES HULLEHJTHAM EEECHEH E. CARY Patented Mar. 19, 1940 UNITED STATES PATENT OFFICE Mich., assignors to Hayes Industries, Inc.,

Jackson, Mich, a corporation of Michigan Application October 6, 1937, Serial No. 167,548

11 Claims.

This invention relates to muiliers for silencing the exhaust noise of internal combustion engines and other engines periodically discharging expanding and noise producing gases.

The tendency in modern automobile design is to reduce the clearance between the bottom of the body of the vehicle and the ground resulting in less space being available for the muffler. Muiiiers have, in the past, been provided with a cylindrical exterior shell for the reason that a cylindrical shell is stronger than a shell of some other shape and is, therefore, less likely to pulsate or breathe and produce objectionable shell noises. However, in the newer designs of automobiles there is not sufficient clearance between the bottom of the vehicle and the ground for accommodating a cylindrical muiller and it is, therefore, necessary to design a muiller of a flattened or non-cylindrical shape.

The present invention contemplates the provision of such a flattened muiiier having an external shell of generally elliptical cross-section, the shell being provided with suitable reinforcing to restrain breathing of the shell and the consequent shell noises. For purposes of economy in weight and manufacturing cost the reinforcing is in the form of an acoustic tube which contributes to the muiiling action of the muiiler.

An object of the invention, therefore, is to provide a flattened muiiier.

Another object of the invention is to provide a muffler having reinforcing in the form of an acoustic tube.

Still another object of the invention is to provide a multiple pass mufller in which one of the passes constitutes a reinforcing element.

Still another object of the invention is to provide a multiple pass muiiler wherein one of the passes may be varied in length to tune the muffler to give the same desired characteristics.

Still another object of the invention is to provide a novel and compact muiliing structure.

These and other objects will be apparent from the following specification when taken with the accompanying drawing in which:

Fig. l is a vertical section through the muiiler comprising the invention, and

Fig.2 is a section on the line 11-11. of Fig. 1.

Referring particularly to the drawing the reference character I indicates the external shell of the muiller which, as disclosed in Fig. 2 is generally elliptical in cross-section. At the left side of Fig. l is a tubular inlet connection 2 and at the right end of Fig. l is a tubular outlet connection 3, the connections 2 and 3 being supported from the end plates 4 and 5. The tube 6 disposed to one side of the shell I communicates with the inlet connection 2 and is supported by bailles I and 8.. Centrally of the shell I is disposed a reinforcing tube S'of generally rectangular configuration. The upper and lower sides thereof conform to the curvature of the shell I and are secured to the same, the sides thereof spacing the top and bottom of the shell i and reinforcing the same against pulsating or breathing due to tube 9 is disposed a baiile ill, the baflles 8 and i0 forming with the end closure plate 5 a chamber 95 and with the bafliing partition l a. chamber i6. It will be observed that the tube 9 is disposed within the chamber I6.

On the opposite side of the shell i from the tube 8 is disposed a tube i1 which is supported at one end by the baffle l0 and provides a communication between the chambers 35 and I6. Both the tubes 6 and I! are secured to the tube 9 along the contacting edges thereof mutually reinforcing each other.

The portion of the tube 6 within the chamber 56 is provided with a plurality of perforations i8 which perforations comprise strips of metal which have been struck out along the edges thereof and drawn radially outwardly from the tube 6.

- Disposed within the tube 9, supported from the closure plate 5 and a plurality of partitions i9 and 20, and telescopically disposed in the tube 9 is a tube 2|. The interior of the tube 9 is sealed from the chambers i6 and I5 by the partitions 20 and the tube 2| communicates at one end with the chamber l6 and at the other end with the outlet 3.

The partitions i9 and 20 define with the tube t and the tube 2| a plurality of resonating chambers 22, the chambers 22 being of different lengths. The tube 2| is provided throughout its length in the portions thereof opposite the resohating chambers 22 with the plurality of perforations 23 which may be of similar character to the perforations l8 and provide a communication between the interior of the tube 2| and the resonating chambers 22. As shown the perforations 23 are diagrammatic of any suitable or desired type of perforation. Opposite the inner end of the tube 2| and in the baiile is an opening 24 providing a communication between the chamber I6 and the chamber 25 disposed between the end closure 4 and the baflle I. In operation the muilier is connected in the exhaust conduit of the internal combustion engine or the like with which it is to be used. The pulsating gases from the engine or the like pass through the tube 8 to the chamber l5. From the chamber IS the gases pass through the tube I! to the chamber l8 from which they are conducted by the tube 2| to the outlet 3. A portion of the gases instead of taking the passage just described will by-pass through the perforations ill in the tube 8 directly to the chamber l6. This by-pass is for the purpose of reducing the back pressure in the mufller which might otherwise be produced and for producing a change in phase between the sound waves accompanying the gases which enter the chamber IS, the change in phase being for the purpose of cancelling the waves out of phase with each other.

The gases passing from the chamber I! through the tube ll enter a compound resonator provided by the chambers 66 and 25 by means of which low frequency sounds are attenuated. In order to tune and slightly vary the characteristics of the mufiler the length of the tube ll may be varied until the characteristics desired are attained,

Gases passing into the tube M from the chamber l6 have the high frequency sound waves accompanying them attenuated in the resonating chambers 22, as a result of the communication provided with the interior 'of the resonating chambers 22, by the perforations 23. The difference in length of the various resonating chambers 22 is for the purpose of resonating different frequencies.

The different engaging parts of the muffler are either welded to one another in any desired manher or are of the slip type connection for the purpose of permitting relative movement between the parts as the circumstances require and as is well known in the art. The multiple pass feature of the invention provides a considerably greater degree of mufiling capacity than could be obtained in a mufiier of the same length not having the multiple pass feature. Furthermore the reinforcing of the mufiler with an acoustic tube makes possible an economy in weight and cost of manufacture which would be impossible if the mufiler had the same muiiling capacity and the reinforcing structure had solely a reinforcing function.

The embodiment of the invention which has been shown and described provides a relative tangential engagement between the tubes 6 and I1 and the reinforcing tube 9. While this relative tangential engagement provides additional strength, the muffler, according to the present invention, could be designed with the relative tubes out of engagement. Such a structure would have substantially the same acoustic properties although it would not be as rigid and, therefore, not as desirable a structure as that disclosed.

Having'thus described our invention what we desire to claim and protect by Letters Patent is:

1. A mufiler of the character described comprising a chamber, a tube projecting therethrough, means providing a communication between one end of said tube and said chamber, said tube directly to said chamber, and means providing an outlet from said chamber.

2. A muiiler of the character described comprising a shell, transverse baflle plates in said shell defining a chamber, a second chamber, a

tube projecting through said first named chamber and communicating with said second chamber, means providing communication between saidsecond chamber and said first named chamber, the interior of said tube to said first named chamber, and means providing an outlet from said first named chamber.

3. A mufiier of the character described com-' prising a shell, a chamber within saidshell, a tube projecting through said chamber, means providing a communication between said tube and said chamber, perforations in the portion of said tube within said chamber constituting a bypass into said chamber from the interior of said tube, and an outlet from said chamber.

4. A mufiler of the character described comprising a shell, a chamber within said shell, a tube projecting through said chamber, means providing a communication between said tube and said chamber, perforations in the portion of said tube within said chamber constituting a by-pass into said chamber from the interior of said tube, and an outlet from said chamber, said outlet comprising means including a resonator.

5. A muiller of the character described comprising a shell, a chamber defined by said shell, a second chamber defined by said shell, a tube projecting through said-first named chamber and communicating with said second chamber, means providing communication between said second chamber and said first named chamber, said tube directly into said first named chamber, and an outlet from said first named chamber.

' 6. A mufller of the character described comprising a shell, a chamber defined by said shell,

' a second chamber defined by said shell, 9. tube projecting through said first named chamber and communicating with said second chamber, means providing communication between said second chamber and said first named chamber, said tube having an opening through the side thereof into said chamber constituting a bypass from said tube directly into said first named chamber, and an outlet from said first named chamber, said outlet comprising means including a resonator.

7. A muflier of the character described comprising a shell, a chamber defined by said shell, 2. second chamber defined by said shell, a tube projecting through said first named chamber and communicating with said second chamber, means providing communication between said second chamber and said first named chamber, perforations in the portion of said tube within said first named chamber constituting a by-pass from the interior of said tube into said first named chamber, and an outlet from said first named chamber, said outlet comprising means including a resonator.

8. A munler of the character described comprising a chamber, a tube projecting therethrough, means including a tube parallel to said first named tube providing a communication between said first named tube and said chamber, said first named tube having an opening through the side thereof into said chamber constituting a by-pass from said first named tube directly to said chamber, and means providing an outlet from said chamber.

9. A muiller of the character described comprising a shell, a chamber defined by said shell, a second chamber defined by said shell, a tube projecting through said first named chamber and communicating with said second chamber, a second tube parallel to ma first nuned tube pro- 73* chamber, said outlet comprising means including a resonator.

10. A muiller of the character described comprising a shell, a chamber within said shell, a second chamber within said shell, a tube project- 0 ing through said first named chamber and communicating with said second chamber, a second tube parallel to said first named tube providing communication between said second chamber and said first named chamber, said first named 5 tube having an opening through the side thereof into said first named chamber constituting a bypass from said first named tube into said first named chamber, and an outlet from said first named chamber, said outlet comprising means including a resonator, said resonator being elongated and parallel to said first and second tubes, said first and second tubes and said resonator being side by side in contacting relation and rigidly secured together for mutual support.

11. A muffler, comprising an outer casing having an inlet and an outlet, means dividing said casing into directly communicating chambers to form a compound resonator, a conduit connected to said inlet and extending through said 10 chambers, and means located in one of said chambers and acoustically communicating with said compound resonator defining a retroverted gas fiow passage connecting with said outlet, said last means including a series of high frequency 15 filter chambers.

CHARLES HOLLERITH. BEECHER B. CARY.

CERTIFICATE OF CORRECTION. Patent No. 2,195,791. March 19, 191 0.

CHARLES HOLLERITH, ET AL:-

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 69, and second column, lines [p5 and 51, claims 1, 2 and 5 respectively, after the word and comma "chamber," insert -said tube having an opening through the side thereof into said chamber constituting a bypass from--; page 5, first column, line 2, claim 9, after the word and comma "chamber," insert -said first named tube having an opening through the side thereof into said first named chamber constituting a by-pass from-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of May, A. D. 191 10.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION Patent No. 2,195,791. March 19, 191p.

CHARLES HOLLERITH, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 69, and second column, lines h-5 and 51, claims 1, 2 and 5 respectively, after the word and comma "chamber," insert -said tube having an opening through the side thereof into said chamber constituting a bypass from--; page 5, first column, line 2, claim 9, after the word and comma chamber," insert --said first named tube having an opening through the side thereof into said first named chamber constituting a by-pass from-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of May, A. D. 191 0.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

